Background of the incidence and etiology of need:
Although several of reconstructive surgical procedures rely on the firm healing or attachment of connective tissue, particularly tendon or ligament, to bone, little is known about the healing process at the tendon-to-bone interface. Since the site of graft fixation to bone represents the weakest area in the early post-transplant period, methods to improve early graft fixation strength have significant clinical application. This is of particular importance in operations on the knee, shoulder, hip, hand, ankle and elbow.
The development of tendon or ligament insertion into bone is poorly understood. The insertion site is mediated by collagen fibers, known as "Sharpey's fibers," which are continuous from tendon into bone. Sharpey's fibers are thought to form in the developing skeleton by progressive mineralization of ligament or periosteal collagen fibers by advancing bone during growth. Studies have indicated that bone heals to tendon by bone ingrowth into the fibrovascular interface tissue which initially forms between the tendon and bone. There is progressive mineralization of the interface tissue with subsequent bone ingrowth into the outer tendon. Despite the evidence that bone grows into collagenous tissue, the mechanism of such bone ingrowth, and the effectiveness and strength of the attachment, remains uncertain. A previous study of tendon-to-bone healing demonstrated the formation of a fibrous tissue interface between the tendon and bone. Rodeo et al., J. Bone and Joint Surgery, 75-A: 1795-1803 (1993).
Accordingly, despite substantial endeavors in this field, there remains a need for an effective method of repair of a functional attachment between connective tissue, such as tendon or ligament, and bone.